- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
The helical shape of certain burrows is interpreted in terms of 2 components of movement which determine the helical path of the burrowing organisms. One is a horizontal component of circular motion as a result of asymmetrical burrowing of a bilaterally symmetrical animal with paired appendages. The other component is inclination to the horizontal plane resulting from an oblique orientation to gravity. Helical burrows may be formed in a variety of environments by unrelated groups of organisms but individual types of burrows may have taxonomic or environmental significance in restricted parts of the geological column. A possible application in determining the direction of gravity at the time of the formation of these burrows would be more generally valid.